Low back pain (LBP) is a common and debilitating medical condition but the vast majority of clinical cases do not have a pathoanatomical diagnosis on the basis of standard clinical tests. Our previous research has shown that, compared with healthy controls, LBP patients have impaired postural control. Furthermore, individuals with a delayed muscle reflex response to sudden trunk loading are known to be at increased risk of sustaining low back injuries. Conservative treatment methods, including pain medication and physical therapy, are generally unsatisfactory. Osteopathic manual therapy (OMT) is a CAM therapy that is being chosen by an increasing number of LBP patients. Our preliminary studies suggest that OMT improves postural control in patients with non-specific LBP, who exhibit such impairments when tested with an unstable sitting task. However, the mechanisms responsible for changes in the control system due to OMT are unknown. We hypothesize that OMT targets impaired or altered function of the neuro-musculoskeletal system arising from a dysfunction in the muscle spindles. Therefore, we will apply a systems science approach to identify elements of the postural control system that change with the use of OMT. Aim 1 of the study will optimize critical tasks for assessing neuromuscular control in LBP patients. These critical tasks will then be used in Aim 2 to identify deficits in postural control of individuals with LBP and to document the effects of OMT on postural control. Aims 3 and 4 are designed to look separately and more specifically at the behavior of reflex responses and muscle spindles. In Aim 3, activation of the erector spinae muscles will be assessed in response to mechanical tapping to determine whether OMT changes the control strategy from co-activation to reciprocal inhibition. Degradations in postural control mediated via feedback from the muscle spindles in LBP patients will be assessed by the response to mechanical muscle vibrations in Aim 4. When completed, this project will deliver sensitive and objective clinical research tools that can model postural control, assess control capabilities, and identify control impairments. These tools will be useful in future clinical studies for characterizing motor control impairments in LBP patients, for standardizing and optimizing CAM treatments aimed at neuro-musculo-skeletal disorders, and for monitoring treatment outcomes.